The present invention relates to a chemical vapor deposition (CVD) process for growing a single-crystalline magnesium oxide film having an improved quality on a silicon (100) substrate having a coated cubic silicon carbide buffer layer.
Magnesium oxide is a transparent and chemically stable material having good electric properties and does not undergo a phase transition even at a high temperature up to its melting temperature of 2852xc2x0 C. Magnesium oxide has been used as a substrate for preparing thereon films of a number of inorganic compounds, i.e., various oxides such as cuprate-based high-Tc superconductors, lithium niobate and barium titanate, as well as nitrides such as gallium nitride and niobium nitride. Also, it is known that films of such oxides and nitrides having excellent properties can be grown on a magnesium oxide film coated on the surface of quartz, silicon, gallium arsenide or sapphire.
There have been reported various methods to prepare a magnesium oxide film on the surface of a single crystal substrate. For example, DeSisto et al. disclose an MgO thin film deposited on sapphire or sapphire coated with alumina by ultrasonic spray pyrolysis [W. J. DeSisto and R L. Henry, xe2x80x9cPreparation and characterization of MgO thin films deposited by spray pyrolysis of Mg(2,4-pentanedionate)2xe2x80x9d, J Crest. Growth 109, 314-317 (1991)]. Also, Yoon et al. and Tarsa et al. describe MgO films deposited on Si and GaAs, respectively, by a sol-gel method [J. G. Yoon, Y. J. Kwag, and H. K. Kim, xe2x80x9cStructural Characterization of Sol-Gel Derived MgO Thin Film on Si Substratexe2x80x9d, J Korean Phys. Soc. 31, 613-616 (1997); and E. J. Tarsa, X. H. Wu, J. P. Ibbetson, J. S. Speck, and J. J. Zinck, xe2x80x9cGrowth of epitaxial MgO films on Sb-passivated (001)GaAs: Properties of the MgO/GaAs interfacexe2x80x9d, Appl. Phys. Lett. 66, 3588-3590 (1995)]; Fork et al. and Nashimoto et al., MgO films formed on Si and GaAs, respectively, by pulsed laser deposition [D. K. Fork, F. A. Ponce, J. C. Tramontana, and T. H. Geballe, xe2x80x9cEpitaxial MgO on Si(001) for Yxe2x80x94Baxe2x80x94Cuxe2x80x94O thin film growth by pulsed laser depositionxe2x80x9d, Appl. Phys. Lett. 58, 2294-2296 (1991); D. K. Fork and G. B. Anderson, xe2x80x9cEpitaxial MgO on GaAs(111) as a buffer layer for z-cut epitaxial lithium niobatexe2x80x9d, Appl. Phys. Lett. 63, 1029-1031 (1993); and K. Nashimoto, D. K. Fork, and T. H. Geballe, xe2x80x9cEpitaxial growth of MgO on GaAs(001) for growing epitaxial BaTiO3 thin films by pulsed laser depositionxe2x80x9d, Appl. Phys. Lett. 60, 1199-1201 (1992)]; Bruley et al. and Kaneko et al., MgO films deposited on GaAs and Si, respectively, by magnetron sputtering [J. Bruley, S. Stemmer. F. Ernst, M. Ruhle, W. Y. Hsu, and R. Raj, xe2x80x9cNanostructure and chemistry of a (100)MgO/(100)GaAs interfacexe2x80x9d, Appl. Phys. Lett. 65, 564-566 (1994); and Y. Kaneko, N. Mikoshiba, and T. Yamashita, xe2x80x9cPreparation of MgO Thin Films by RF Magnetron Sputteringxe2x80x9d, Jpn. J. Appl. Phys. 30, 1091-1092 (1991)]; and Hung et al. and Masuda et al., MgO films deposited on GaAs and/or Si, by electron-beam evaporation [L. S. Hung, R. Zheng, and T. N. Blanton, xe2x80x9cEpitaxial growth of MgO on (100)GaAs using ultrahigh vacuum electron-beam evaporationxe2x80x9d, Appl. Phys. Lett. 60, 3129-3131 (1992); and A. Masuda and K. Nashinioto, xe2x80x9cOrientation of MgO Thin Films on Si(100) and GaAs(100) Prepared by Electron-Beam Evaporationxe2x80x9d, Jpn. Appl. Phys. 33, L793-L796 (1994)].
For epitaxially growing a film of good quality, one needs to consider such factors as lattice match between the substrate and the film to be deposited thereon, crystal structures and the nature of chemical bonds thereof. However, when magnesium oxide (lattice constant: 0.4213 nm) whose lattice oxygen and magnesium atoms respectively are of a face-centered cubic structure is grown on a silicon single crystal (lattice constant: 0.5431 nm) having the diamond structure, it is difficult to obtain an MgO film of good quality due to a very large lattice mismatch of xe2x88x9222.4%.
Accordingly, it is an object of the present invention to provide a method for growing a single-crystalline MgO film having improved quality on a Si(100) substrate.
In accordance with one aspect of the present invention, there is provided a method for growing a single-crystalline MgO film on a Si(100) substrate, which comprises depositing a cubic SiC buffer layer on the substrate and forming a MgO film on the SiC layer using a chemical vapor deposition process.